Most prior ball release devices store the ball in the fluid stream and use circulation to transport it to the seat. Several problems can occur with this design. The ball may not release because the carrier gets clogged with debris from the mud. The carrier can become worn resulting in premature release of the ball. The ball is released during high circulation. It can slam against a seat and create high pressure spikes that can damage other equipment. The high circulation rates around the ball can erode parts of it causing it to not hold pressure even if it lands on the ball seat. Some examples of prior designs that have the ball in the circulating path are U.S. Pat. Nos. 6,390,200; 6,220,360; and 5,960,881. U.S. Pat. No. 4,171,019 shows a cement float shoe with a ball in a side pocket such that it can be displaced against a ball seat if the flow direction reverses. Balls have been used to fix a range of motion of a sleeve valve member, as shown in U.S. Pat. No. 4,406,335.
What the prior devices lacked is addressed by the present invention. The ball is retained near its intended seat near the bottom of the hole. It is retained out of the flowing stream. The ball discharge procedure is such that ball release occurs after circulation is stopped and not during circulation. Once the ball is released it is prevented from reentering its original storage location. These and other benefits of the present invention will be more apparent to those skilled in the art from a review of the description of the preferred embodiment and the claims, which appear below.